Hi, I run the code src/snes/examples/tutorials/ex5.c with options:
* mpirun -n 8 ./ex5 -pc_type mg \ -ksp_monitor\ -pc_mg_levels 3 \ -pc_mg_galerkin \ -da_grid_x 17 \ -da_grid_y 17 \ -mg_levels_ksp_norm_type unpreconditioned \ -snes_monitor \ -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.5,1.1 \ -mg_levels_pc_type sor \ -pc_mg_type \* I run this script several times, but at each time, the residual norms have some tiny differences ( these should not happen). For example: Case 1: * 0 SNES Function norm 1.188788066192e+00 0 KSP Residual norm 1.573384253521e+00 1 KSP Residual norm 3.616321708396e-02 2 KSP Residual norm 2.780221563755e-04 3 KSP Residual norm 2.194662354037e-06 1 SNES Function norm 5.125240595190e-03 0 KSP Residual norm 1.217284338266e-01 1 KSP Residual norm 1.774247017346e-04 2 KSP Residual norm 2.557118591292e-06 3 KSP Residual norm 1.622173269367e-08 2 SNES Function norm 3.922335995111e-05 0 KSP Residual norm 9.960745924876e-04 1 KSP Residual norm 1.273916336665e-06 2 KSP Residual norm 1.571259383270e-08 3 KSP Residual norm 1.250266145356e-10 3 SNES Function norm 2.662898279023e-09 * Case 2: * 0 SNES Function norm 1.188788066192e+00 0 KSP Residual norm 1.573384253521e+00 1 KSP Residual norm 3.616321708396e-02 2 KSP Residual norm 2.780221563755e-04 3 KSP Residual norm 2.194662354037e-06 1 SNES Function norm 5.125240595190e-03 0 KSP Residual norm 1.217284338266e-01 1 KSP Residual norm 1.774247017347e-04 2 KSP Residual norm 2.557118591292e-06 3 KSP Residual norm 1.622173269367e-08 2 SNES Function norm 3.922335995108e-05 0 KSP Residual norm 9.960745924862e-04 1 KSP Residual norm 1.273916336654e-06 2 KSP Residual norm 1.571259383257e-08 3 KSP Residual norm 1.250266145346e-10 3 SNES Function norm 2.662898285038e-09 * These differences are marked by red color. So here, I was wondering there are any explanations why these happen? Thanks, Fande,
